While mild or warm spring days have been disappointingly few, most of the usual migratory birds have returned to our region, as if programmed more by the calendar than weather conditions or temperatures.

We have five species of cuckoos with us again, along with dusky woodswallow, olive-backed oriole, reed warbler, fairy martin and tree martin.

Some of these birds spend the winter in northern Australia, but some of our cuckoos and our tree martins probably go to New Guinea or Indonesia.

A greenshank sighting at Brewster last weekend is of interest, because this bird is from southern Siberia. No sandpipers or stints – also Asian migrants – have yet been reported this season, despite a recent check at Lake Goldsmith. The same applies to the Japanese Latham’s snipe, but this bird is sure to be back already in suitable marshy places.

Yellow-faced honeyeaters and grey fantails, while not generally regarded as migrants, have increased in numbers in recent weeks. A large proportion of our local population of these two species undertakes migratory movements each year.

Birds normally return when there is sufficient food for them. In many cases their food is insects – particularly flying insects – and many of these insects are not numerous until milder weather arrives. Olive-backed orioles eats larger insects, while cuckoos eat mainly caterpillars, which are not so dependent on warm weather. The reed warbler gets its specialised insect food from reeds, rushes and sedges.

Sandpipers and other similar small Asian waders feed on tiny crustaceans and worms. This food will increase as wetlands warm up.

From late September to mid-October another range of bird migrants will arrive as their specialised foods become more abundant with warmer weather.

MORE CORELLAS

Little corellas are gradually increasing in the region. We have had regular visits from these birds in summer and autumn for the last few years; now they have been seen in winter as well.

The apparent extension of season may indicate that the recent visitors are becoming residents. Winter observations have been made at Learmonth, where little corellas mix with larger numbers of long-billed corellas.

The long-billed corella remains common in the district year-round. It too was once a rarity that has now become widespread and numerous.

The species can be hard to tell apart unless seen clearly. The long-billed corella has red markings on its throat and chest, while the little corella is whiter, with a more prominent upright crest.